What you say to a person when you have been one-upped by said person in an argument or debate of some sort. Pretty much just lets you try to get the last word in when you have no other retort.

Person A: "Oh man! We got jumped by like twelve guys and kicked all their asses!"
Person B: "Actually there were three; Steve McPeterson, Dave Ellis, and that guy that works the Wendy's drive-thru."
Person A: "Well, you forgot Poland."